Fungi wars: parasites use 'guerrilla tactics' and chemical weapons to infect animal hosts

Parasitic fungi which enter animals' bodies and feed on their insides use guerrilla warfare-style tactics, penetrating and destroying the immune system with small troops before a large scale attack, a new study has revealed.

In theory, an animal's immune system should be able to detect and fight off parasites before they gain a significant foothold, but some types of fungi are able to bypass even the best defences.

"Evolution has turned [the fungi] into a highly sophisticated and efficient war machine, with everything from ammunition production lines to special operation units," said lead researcher Wang Chengshu, of the Chinese Academy of Sciences' Shanghai Institute for Biological Science.

In a paper in the US journal Proceedings of the National Academy of Science, Wang and his colleagues described for the first time how fungi generated and used small chemical agents to infiltrate prospective hosts' immune systems and open a gate for further infection.

The scientists identified a "chemical weapon production line" consisting of seven genes in Beauveria bassiana, one of the deadliest fungi to insects. The genetic "factory" produces a chemical called bibenzoquinone oosporein, used against potential hosts to weaken them before infection.

"The production of the chemical is an extremely sophisticated but organised process, with every gene playing a specific function like workers in a production line," Wang said.